1. Field of the Invention
The invention relates to a power managing apparatus; in particular, to a power managing apparatus, a DC-DC control circuit, and a method for enabling a chip capable of saving additional enable pins to enhance function expandability.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 illustrates a schematic diagram of the pulse width modulation integrated circuit (PWM IC) and the driver coupled in the power converter and the signal transmissions between them in the prior art.
As shown in FIG. 1, the pulse width modulation integrated circuit PWM IC of the power converter 1 has pins P1˜P3, wherein the pin P1 is an enable pin used for receiving an input signal SYS from the system to control the pulse width modulation integrated circuit PWM IC itself operated in an enable state or a disable state; the pin P2 is a control pin coupled to the driver DRIVER and used for transmitting an enable control signal DRON to the driver DRIVER to control the driver DRIVER operated in the enable state or the disable state; the pin P3 is used for outputting a pulse width modulation signal PWM to the driver DRIVER when the pulse width modulation integrated circuit PWM IC is operated in the enable state.
The driver DRIVER of the power converter 1 has pins P4˜P5 wherein the pin P4 is an enable pin coupled to the control pin P2 of the used for the pulse width modulation integrated circuit PWM IC and used for receiving the enable control signal DRON provided by the control pin P2 to control the driver DRIVER itself operated in the enable state or the disable state; the pin P5 is an input pin coupled to the pin P3 of the pulse width modulation integrated circuit PWM IC and used for receiving the pulse width modulation signal PWM when the driver DRIVER is operated in the enable state.
It should be noted that when the enable control signal DRON provided by the control pin P2 of the pulse width modulation integrated circuit PWM IC is high-level, the driver DRIVER will be operated in the enable state; when the enable control signal DRON provided by the control pin P2 of the pulse width modulation integrated circuit PWM IC is low-level, the driver DRIVER will be operated in the disable state.
However, since the pulse width modulation integrated circuit PWM IC in the power converter has limited number of pins, if one pin (e.g., the control pin P2) of the pulse width modulation integrated circuit PWM IC is specifically used to control the driver DRIVER operated in the enable state or the disable state, there will be one less pin to be set for other functions and the function expandability of the pulse width modulation integrated circuit PWM IC will be severely limited.